gpx.studio/gpx/src/io.ts

import { XMLParser, XMLBuilder } from 'fast-xml-parser';
import { GPXFileType } from './types';
import { GPXFile } from './gpx';

const attributesWithNamespace = {
    RoutePointExtension: 'gpxx:RoutePointExtension',
    rpt: 'gpxx:rpt',
    TrackPointExtension: 'gpxtpx:TrackPointExtension',
    PowerExtension: 'gpxpx:PowerExtension',
    atemp: 'gpxtpx:atemp',
    hr: 'gpxtpx:hr',
    cad: 'gpxtpx:cad',
    Extensions: 'gpxtpx:Extensions',
    PowerInWatts: 'gpxpx:PowerInWatts',
    power: 'gpxpx:PowerExtension',
    line: 'gpx_style:line',
    color: 'gpx_style:color',
    opacity: 'gpx_style:opacity',
    width: 'gpx_style:width',
};

const floatPatterns = [
    /[-+]?\d*\.\d+$/, // decimal
    /[-+]?\d+$/, // integer
];
function safeParseFloat(value: string): number {
    const parsed = parseFloat(value);
    if (!isNaN(parsed)) {
        return parsed;
    }
    for (const pattern of floatPatterns) {
        const match = value.match(pattern);
        if (match) {
            return parseFloat(match[0]);
        }
    }
    return 0.0;
}

export function parseGPX(gpxData: string): GPXFile {
    const parser = new XMLParser({
        ignoreAttributes: false,
        attributeNamePrefix: '',
        attributesGroupName: 'attributes',
        removeNSPrefix: true,
        isArray(name: string) {
            return (
                name === 'trk' ||
                name === 'trkseg' ||
                name === 'trkpt' ||
                name === 'wpt' ||
                name === 'rte' ||
                name === 'rtept' ||
                name === 'gpxx:rpt'
            );
        },
        attributeValueProcessor(attrName, attrValue, jPath) {
            if (attrName === 'lat' || attrName === 'lon') {
                return safeParseFloat(attrValue);
            }
            return attrValue;
        },
        transformTagName(tagName: string) {
            if (attributesWithNamespace[tagName]) {
                return attributesWithNamespace[tagName];
            }
            return tagName;
        },
        parseTagValue: false,
        tagValueProcessor(tagName, tagValue, jPath, hasAttributes, isLeafNode) {
            if (isLeafNode) {
                if (tagName === 'ele') {
                    return safeParseFloat(tagValue);
                }

                if (tagName === 'time') {
                    return new Date(tagValue);
                }

                if (
                    tagName === 'gpxtpx:atemp' ||
                    tagName === 'gpxtpx:hr' ||
                    tagName === 'gpxtpx:cad' ||
                    tagName === 'gpxpx:PowerInWatts' ||
                    tagName === 'gpx_style:opacity' ||
                    tagName === 'gpx_style:width'
                ) {
                    return safeParseFloat(tagValue);
                }

                if (tagName === 'gpxpx:PowerExtension') {
                    // Finish the transformation of the simple <power> tag to the more complex <gpxpx:PowerExtension> tag
                    // Note that this only targets the transformed <power> tag, since it must be a leaf node
                    return {
                        'gpxpx:PowerInWatts': safeParseFloat(tagValue),
                    };
                }
            }

            return tagValue;
        },
    });

    const parsed: GPXFileType = parser.parse(gpxData).gpx;

    // @ts-ignore
    if (parsed.metadata === '') {
        parsed.metadata = {};
    }

    return new GPXFile(parsed);
}

export function buildGPX(file: GPXFile, exclude: string[]): string {
    const gpx = file.toGPXFileType(exclude);

    let lastDate = undefined;
    const builder = new XMLBuilder({
        format: true,
        ignoreAttributes: false,
        attributeNamePrefix: '',
        attributesGroupName: 'attributes',
        suppressEmptyNode: true,
        tagValueProcessor: (tagName: string, tagValue: unknown): string | undefined => {
            if (tagValue instanceof Date) {
                if (isNaN(tagValue.getTime())) {
                    return lastDate?.toISOString();
                }
                lastDate = tagValue;
                return tagValue.toISOString();
            }
            return tagValue.toString();
        },
    });

    if (!gpx.attributes) gpx.attributes = {};
    gpx.attributes['creator'] = gpx.attributes['creator'] ?? 'https://gpx.studio';
    gpx.attributes['version'] = '1.1';
    gpx.attributes['xmlns'] = 'http://www.topografix.com/GPX/1/1';
    gpx.attributes['xmlns:xsi'] = 'http://www.w3.org/2001/XMLSchema-instance';
    gpx.attributes['xsi:schemaLocation'] =
        'http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd http://www.garmin.com/xmlschemas/GpxExtensions/v3 http://www.garmin.com/xmlschemas/GpxExtensionsv3.xsd http://www.garmin.com/xmlschemas/TrackPointExtension/v1 http://www.garmin.com/xmlschemas/TrackPointExtensionv1.xsd http://www.garmin.com/xmlschemas/PowerExtension/v1 http://www.garmin.com/xmlschemas/PowerExtensionv1.xsd http://www.topografix.com/GPX/gpx_style/0/2 http://www.topografix.com/GPX/gpx_style/0/2/gpx_style.xsd';
    gpx.attributes['xmlns:gpxtpx'] = 'http://www.garmin.com/xmlschemas/TrackPointExtension/v1';
    gpx.attributes['xmlns:gpxx'] = 'http://www.garmin.com/xmlschemas/GpxExtensions/v3';
    gpx.attributes['xmlns:gpxpx'] = 'http://www.garmin.com/xmlschemas/PowerExtension/v1';
    gpx.attributes['xmlns:gpx_style'] = 'http://www.topografix.com/GPX/gpx_style/0/2';

    if (gpx.trk.length === 1 && (gpx.trk[0].name === undefined || gpx.trk[0].name === '')) {
        gpx.trk[0].name = gpx.metadata.name;
    }

    return builder.build({
        '?xml': {
            attributes: {
                version: '1.0',
                encoding: 'UTF-8',
            },
        },
        gpx: removeEmptyElements(gpx),
    });
}

function removeEmptyElements(obj: GPXFileType): GPXFileType {
    for (const key in obj) {
        if (
            obj[key] === null ||
            obj[key] === undefined ||
            obj[key] === '' ||
            (Array.isArray(obj[key]) && obj[key].length === 0)
        ) {
            delete obj[key];
        } else if (typeof obj[key] === 'object' && !(obj[key] instanceof Date)) {
            removeEmptyElements(obj[key]);
            if (Object.keys(obj[key]).length === 0) {
                delete obj[key];
            }
        }
    }
    return obj;
}